feat: 添加新武器彩虹旗和紫水晶簇，调整饲料属性和数值

refactor: 重构子弹生成逻辑，支持分裂和折射效果

fix: 修复掉落物拾取范围和碰撞检测问题

style: 优化UI显示，添加武器品质和类型标签

docs: 更新字段描述，调整部分饲料名称和分类

perf: 优化数学工具函数，添加随机数处理工具

test: 调整波次生成逻辑，添加新敌人类型

build: 添加新资源文件和相关导入配置

scripts/Tools/EntityTool.gd

@@ -7,4 +7,20 @@ static func fromHurtbox(node: Node) -> EntityBase:
 			var entity = texture.get_parent()
 			if entity is EntityBase:
 				return entity as EntityBase
-	return null
+	return null
+static func findClosetEntity(to: Vector2, fromTree: SceneTree, player: bool = false, mob: bool = false, excludes: Array[EntityBase] = []) -> EntityBase:
+	var result = null
+	var lastDistance = INF
+	var nodes = []
+	if player:
+		nodes += fromTree.get_nodes_in_group("players")
+	if mob:
+		nodes += fromTree.get_nodes_in_group("mobs")
+	for entity in nodes:
+		if entity is EntityBase and entity not in excludes:
+			if to.distance_to(entity.position) < lastDistance:
+				lastDistance = to.distance_to(entity.position)
+				result = entity
+	return result
+static func findClosetPlayer(to: Vector2, fromTree: SceneTree, excludes: Array[EntityBase] = []) -> EntityBase:
+	return findClosetEntity(to, fromTree, true, false, excludes)